Image sensors (image pickup devices) for use in photographing apparatuses such as digital still cameras, digital video cameras, or the like, sometimes create moiré and false color, etc., that do not originally exist on an object if light rays emanating from the object contain components of spatial frequency that exceeds the limit spatial frequency of the image sensor. To reduce the occurrence of such phenomena, an optical low-pass filter is conventionally used. On the other hand, if an optical low-pass filter is used, resolving power, a sense of resolution and contrast deteriorate.
Whereas, an optical low-pass filter (Patent Literature 1) and a digital camera (Patent Literature 2) have been proposed as technologies for preventing moiré and false color, etc., from occurring without the use of a low-pass filter. The optical low-pass filter is provided with an variable apex-angle prism which is disposed in a photographing optical system and an exciting driver which excites and drives the variable apex-angle prism to vary the direction of object-emanating light rays which emerge from the variable apex-angle prism, wherein the optical low-pass filter is capable of obtaining optical low-pass filter effect by varying the direction of the object-emanating light rays by exciting the variable apex-angle prism, and the digital camera obtains an optical low-pass filter effect by receiving the object-emanating light rays via a plurality of pixels while moving an image sensor along a predetermined path.